Effect of Storage Temperature on Freeze Denaturation of Carp Myofibrils with KCl or Nacl.

Abstract

The effect of storage temperature on the freeze denaturation of carp myofibrils with NaCl was compared with that of KCl in the range of -3 ?? -30°C. The amount of unfrozen water was meas-ured by a calorimeter at each storage temperature, and the salt concentration was then calculated. The extent of denaturation was monitored by changes in Ca-, Mg-, and EDTA-ATPase activity, apparent rate constant of freeze inactivation, viscosity, ATP-sensitivity, and soluble actin. These changes reached their maximum levels at -13°C with KCl, and -8 ?? -18°C with NaCl. The apparent rate constant with KCl was less than that with NaCl in the -3 ?? -30°C range. The ex-tent of denaturation increased with a decrease in temperature from -3 to -13°C, and decreased with a decrease in temperature from -13°C to -30°C. These findings show that freeze denaturation above -13°C is caused by the concentration of unfrozen salt solution, while that below -13°C is caused by the decrease in the amount of unfrozen solution.